/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

package org.apache.iotdb.commons.schema.tree;

import org.apache.iotdb.commons.path.PartialPath;

/**
 * This class defines a dfs-based traversing algorithm with limit and offset based on
 * AbstractTreeVisitor.
 *
 * <p>This class takes two extra parameters as input:
 *
 * <ol>
 *   <li>int limit: the max count of the results collected by one traversing process.
 *   <li>int offset: the index of first matched node to be collected.
 * </ol>
 */
public abstract class AbstractTreeVisitorWithLimitOffset<N extends ITreeNode, R>
        extends AbstractTreeVisitor<N, R> {

    protected final int limit;
    protected final int offset;
    protected final boolean hasLimit;

    protected int count = 0;
    protected int curOffset = -1;

    protected AbstractTreeVisitorWithLimitOffset(
            N root, PartialPath pathPattern, int limit, int offset, boolean isPrefixMatch) {
        super(root, pathPattern, isPrefixMatch);
        this.limit = limit;
        this.offset = offset;
        hasLimit = limit != 0;
    }

    @Override
    public boolean hasNext() {
        if (hasLimit) {
            return count < limit && super.hasNext();
        }

        return super.hasNext();
    }

    @Override
    protected void getNext() {
        if (hasLimit) {
            if (curOffset < offset) {
                while (curOffset < offset) {
                    super.getNext();
                    curOffset += 1;
                    if (nextMatchedNode == null) {
                        return;
                    }
                }
            } else {
                super.getNext();
                curOffset += 1;
            }
        } else {
            super.getNext();
        }
    }

    @Override
    public R next() {
        R result = super.next();
        if (hasLimit) {
            count++;
        }
        return result;
    }

    @Override
    public void reset() {
        super.reset();
        count = 0;
        curOffset = -1;
    }

    public int getNextOffset() {
        return curOffset + 1;
    }
}
